[NOUPSTREAM] Build Kernel package in GitLab CI

Build a Kernel .deb pacakge in GitLab CI.

Signed-off-by: Christopher Obbard <chris.obbard@collabora.com>

.gitignore

@@ -102,6 +102,7 @@ modules.order
 !.kunitconfig
 !.mailmap
 !.rustfmt.toml
+!.gitlab-ci.yml
 
 #
 # Generated include files

.gitlab-ci.yml

+default:
+  image: debian:testing
+  tags:
+    - bookworm
+
+stages:
+  - build
+
+.build debian package:
+  stage: build
+  tags:
+    - ultra-heavyweight
+  cache:
+    when: on_success
+    key: $CI_COMMIT_REF_SLUG
+    paths:
+      - ccache
+  variables:
+    DEBIAN_FRONTEND: noninteractive
+    GIT_SUBMODULE_STRATEGY: normal
+    ARCH: amd64
+    DEFCONFIG: defconfig
+    CCACHE_BASEDIR: $CI_PROJECT_DIR
+    CCACHE_DIR: $CI_PROJECT_DIR/ccache
+  before_script:
+    - apt update
+    - apt install -y devscripts
+                     build-essential
+                     crossbuild-essential-arm64
+                     bc
+                     bison
+                     ccache
+                     flex
+                     rsync
+                     kmod
+                     cpio
+                     libelf-dev
+                     libssl-dev
+    # Setup ccache
+    - export PATH="/usr/lib/ccache:$PATH"
+    - ccache -s
+  script:
+    - make $DEFCONFIG
+
+    - make -j$(nproc) $ADDITIONAL_BUILD_CMD bindeb-pkg
+    - mkdir artifacts && dcmd mv ../*.changes artifacts/
+  artifacts:
+    paths:
+      - artifacts
+
+build arm64 debian package:
+  extends: .build debian package
+  variables:
+    ARCH: arm64
+    CROSS_COMPILE: aarch64-linux-gnu-
+    ADDITIONAL_BUILD_CMD: KBUILD_IMAGE=arch/arm64/boot/Image